Boundary layer suction from the surfaces of aircraft components that are exposed to streaming air is used to reduce the flow resistance and to increase the achievable lift by avoiding early change from a laminar flow to a turbulent flow. In unfavourable environmental conditions, there is a danger of the perforations in the outer skin, which perforations are used for boundary layer suction, icing up, or for an undesirable quantity of water entering the vacuum channel system that is connected to said perforations.